zemog

91gt, i was checking codes with a code checker and i was performiing a timing check to see if my advance was working right. on the first test i set the base at 10 degrees, turned on the checker and it advanced the timing to 30deg. adv., which is correct, for the sake of argument i ran a second test at base 14 deg., turned on checker and it only advanced the timing to 20 deg.. what is the problem , is there anything i can change or is this a computer issue or what.